visited attic of a house built in 1972 in columbus ohio. problem is condensation and frost on underside of roof sheathing in attic. air turnover is 6.6. attic floor has been sealed and all known penetrations from conditioned space to attic have been sealed. attic has five soffit vents in front and 5 in back. homeowner added three aura vents on top of roof. link following if anyone wants information. (http://www.homedepot.com/buy/active-ventilation-12-in-aluminum-aura...)
homeowner had foam blown into walls two years ago. He is not sure when condensation issue began as he only observed 2 years ago. homeowner keeps a humidistat in attic as humidity sometimes runs above 80%.
any suggestions, knowledge, expertise would be appreciate as I do not know what to recommend.
>>attic floor has been sealed and all known penetrations from conditioned space to attic have been sealed
Is this what the owner stated, or something that you inspected?
>> attic has five soffit vents in front and 5 in back
Standard recommendation would be to add ridge vents and possibly remove hat vents.
>> homeowner keeps a humidistat in attic as humidity sometimes runs above 80%
What does the humidistat control?
This sounds like a typical moisture investigation. Is the basement damp? What's the story with the ductwork? What are moisture levels in the house? Do they have a humidifier? Are the bath fans correctly ducted out? It can be hard to figure out the exact cause in one trip, and it may have multiple causes.
I inspected attic floor early in process and it was decent then. Since this point homeowner covered attic stair, sealed around exhaust fan and sealed bypassess from front porch to attic.
I did not mean to say humidistat, he has a remote humdiity sensor monitoring levels.
there is no ductwork in attic, moisture in house is around 50%. moisture in basement is a little high (don't know reading) ducts you saw in attic were for bathroom fans.
there are baffles protecting the. House is very normal except the turbines. not sure if they are proper or not.
I'm reading this discussion with interest and agree that it could be more than one water source or venting issue -- I'm just adding that in the picture of the house there is a good size water source in the backyard near the house (the pool) and if the prevailing summer wind for the site is blowing across the pool and into the back of the house, the attic soffit vents (and the open windows & doors, if any) on that side may be catching the extra humidity. I guess this would be answered by a close examination of when the humidity is worst in the attic -- just pool open season or is rainy spring and fall bad as well.
thank you for the suggestion, I had not considered the pool. condensation (sometimes frost)is during the winter months as well. I do not know if the pool is covered or drained during the winter months, but I can find out.
---while you're checking on the pool -- how about leaks (or excessive splashing) into the surrounding ground making the basement damper. The question would be, do they have to top off the pool often to keep the water level up.
while we're discussing gross water infiltration...I took another look at the house picture and have another question...how's the drainage off the roof? The land looks pretty level and if the down spouts don't have extentions or if the gutters aren't functioning well...A rain event of say 1" on that size roof can yield hundreds of gallons of water at the foundation. Couple that with soil that has a high clay content or a basement wall that is not sealed well and you get the picture... swimming pool in the basement not the backyard.
The basement of every house we've reno'd has had an improvement in the dampness level by just making sure the gutters, downspouts, extentions and site grading was functioning properly. I like to say, "build a roof in your yard". Your grading (5% slope) away from your house is a must.
As I understand it, the homeowner did the airsealing. Was a blower door test with IR completed after the sealing? And the points made regarding soffit baffles and a ridge vent are also good points.
I agree on the soffit baffles -- my 1990's ranch has blown FG installed in the attic and vented soffit -- they used faced FG from ceiling joist bays bent up to the rafter bays to chorral the blown FG and rafter mates on underside of the roof deck and ridge vent so there's great airflow and no moisture problem.
What is the RH of the House? What is the RH out side I have seen a water leak up the RH 40% - I saw a roof leak next to condenstat line dump 4 gal a day into the home. I have seen dryer vent into attic and rot all the plywood in attic. I have seen water/plumbing back up in craw space run all the way to attic and frost on nails. Must find the water
I will ask for a record from homeowner. I think he is keeping records of temp and humidity. we have eliminated all sources of water into attic except moisture in basement (not excessive water) just basement dampness.